Nyāya Sūtras

The Nyaya-sutras were composed by Aksapada Gautama (c. 2nd century BC). The sutras contain five chapters, each with two sections.

The utlimate purpose of the Nyaya Sutras is the attainment of salvation, i.e., complete freedom from pain--and salvation is attained by knowledge of the 16 categories, which are means of valid knowledge (pramana); objects of valid knowledge (prameya); doubt (samshaya); purpose (prayojana); example (drstanta); conclusion (siddhanta); the constituents of a syllogism (avayava); argumentation (tarka); ascertainment (nirnaya); debate (vada); disputations (jalpa); destructive criticism (vitanda); fallacy (hetvabhasa); quibble (chala); refutations (jati); and points of the opponent's defeat (nigrahasthana).

According to the Nyaya Sutras, there are four means of attaining valid knowledge: perception, inference, comparison, and verbal testimony. The sutras implicitly develop a theory of causation. Cause and effect should be homogeneous in nature, and yet the effect is a new beginning and was not already contained in the cause. The Buddhist thesis that all things are negative in nature (inasmuch as a thing's nature is constituted by its differences from others) is rejected, as is the view that all things are eternal or that all things are noneternal. Both these latter views are untrue to experience. Thus, the resulting metaphysics admits two kinds of entities: eternal and noneternal. The whole is a new entity over and above the parts that constitute it. Also, the idea that God is the material cause of the universe is rejected. God is viewed as the efficient cause, and human deeds produce their results under the control and cooperation of God.

The Nyaya Sutra supports a five-membered syllogism with the following structure:

• 1. This hill is fiery (pratijna: a statement of that which is to be proved).
• 2. Because it is smoky (hetu: statement of reason).
• 3. Whatever is smoky is fiery, as is a kitchen (udaharana: statement of a general rule supported by an example).
• 4. So is this hill (upanaya: application of the rule of this case).
• 5. Therefore this hill is fiery (nigamana: drawing the conclusion).

The characteristic feature of the Nyaya syllogism is its insistence on the example--which suggests that the Nyaya logician wanted to be assured not only of formal validity but also of material truth. Five kinds of fallacious "middle" (hetu) are distinguished: the inconclusive (savyabhicara), which leads to more conclusions than one; the contradictory (viruddha), which opposes that which is to be established; the controversial (prakaranasama), which provokes the very question that it is meant to settle; the counterquestioned (sadhyasama), which itself is unproved; and the mistimed (kalatita), which is adduced "when the time in which it might hold good does not apply."